Testing has shown imprecise idler angular alignment is often a significant source of power loss on a conveyor as well as contributing to the wear and tracking instability of belt conveyors. When an idler roll is not perpendicular to the belt direction of travel, the belt/idler roll condition commonly referred to as “sliding parallel to the roll axis” develops. This continual sliding is resisted by an axial force. This force has lateral and longitudinal components. The longitudinal component resists belt movement, which condition requires additional power. The lateral force component causes roll and belt wear due to the belt undesirably wandering along its designated path. Alignment is focused on the center roll of a three roll idler set since the center roll has the most load and therefore exerts the greatest axial friction force. Minimizing this force is the purpose of the present invention.
The most common current measurement methods to prevent the aforementioned problem is to use a tape measure in various imprecise ways or, even worse, rely on visual references to support stringers. Positioning a tape measure is usually a two person job and requires two cross measurements for angular deviation measurements. Measuring to adjacent idlers is not the most relevant point of reference since both idlers can be misaligned without verifying alignment to the belt. The outer, or wing, idler roll is the most available but does not offer an easy or accurate location on its exposed circumference for measurement. Alternatively, points on the idler frame can be used but access to the same point on adjacent or near idlers is often obstructed. None of these points are as beneficial as a direct measurement to the center roll since alignment of all of the idler rolls to each other and to the frame may not be tightly controlled by manufacturers. The center roll carries the most load and therefore is most resistance to belt movement if not well aligned.
WO1995008094 A1 (incorporated herein by reference in its entirety) by inventor Geoff Edwards is dated 1995 and shows a device apparently used in a product produced by Applied Resolution Technologies (ART), an Australian company, that is used for idler alignment. The ART method uses a laser in a manner to be perpendicular to an idler roll so a common datum is created to allow measurement to common features, such as the roll ends, of nearby idlers. The mounting method and principle of operation of the Edwards/ART measurement device/system is difficult to use and is problematical in accomplishing its desired result.
U.S. Pat. No. 3,664,489 A (also incorporated herein by reference in its entirety) shows an apparatus and method for aligning belt conveyor components such as idler frames and pulleys but is difficult to use.
Accordingly, there is a need for a method and apparatus to overcome the aforementioned problems and disadvantages of the prior art.